Looks like enolate formation and breakdown. You should find something about it in an organic chemistry text, under the aldol reaction. Can't say I know very much about it, but there may be some organic chemists here that can do better.

If you're pressing and sintering powders, find another supplier and keep the stuff under argon. If you're messsing around with other uses, you can try a hot hydrogen stream --- you'll probably get enough H dissolved in the B to screw you up, though. Wet methods? Forget it.